By on August 1, 2013

SLK32AMG_front1

Martin writes:

Hi Sajeev,

I’m writing you because I’ve searched and asked model-specific forums, and mechanics, to no avail. I have the last of the 1st Gen SLK AMGs. I love this car, and I’ve loved it since the first non-AMG launched in the late 90s. Overall, it’s well maintained – a trend which I continue – and I’ve had it for a few years. I have one major issue.

The Xenon headlights will blink out randomly – the issue is solved by flicking the lights completely off, and then back on…it almost always happens on my passenger side headlight, but I’ve seen it happen on the driver’s side as well though this is rare. It usually happens on a bump, or on impact of some kind, like a speed bump, braking, or closing the hood, and can occur every few minutes (usually in wet weather – thought doesn’t ALWAYS happen in wet weather) or not at all for several months (usually dry weather).

Mechanics have diagnosed it as anything ranging from a bad ballast (doesn’t make sense to me as ballasts either work or the don’t) to a faulty bulb. One mechanic put some kind of lubrication on the contacts with the bulb and the problem went away for several months – even in wet weather, but I’m not sure if this was a solution or coincidence. Due to two factors – higher incidence of occurrence in wet weather – and the presence of condensation in the passenger’s side bulb (the worst offender) – I think there’s a short somewhere. I’ve checked the wiring and it seems ok. No one can give me a convincing reason as to why I should just replace the whole headlight assembly (an expensive proposal) – and although I realize AMG cars are pricier to maintain and I don’t mind spending, I also don’t want to do it unnecessarily just to discover that it’s a short in some kind of control module or peripheral piece.

Have you ever heard of this? Looking forward to your input.

Sajeev answers:

Not an easy question, but luckily you want what’s best for the car. Which isn’t cheap for a German car of this era. I still have nightmares about attempting to fix anything on my Father’s former 1996 BMW 750iL…beautiful, glorious nightmares I tell you!

Proper Mercedes-Benz shop manuals for this car are a must…but first…give this a shot:

A problem this intermittent, normally happening on one side means there’s an easy diagnostic route: switch headlights (first) and ballasts (second, assuming there are two, so RTFM) between left and right headlights and see if the flickering pattern changes.  If so great…you probably found your offender.

If not…well…

I am somewhat confident that voltage irregularities in failing ballasts can cause this, but the bulbs themselves aren’t free from guilt.  I worry because you flick’d them off/on: hot re-strikes on many older HID bulbs is a big no-no.  BIIIIIG no-no, as I learned when converting the horrible headlights on my 1995 Mark VIII to the HIDs of the 1996 model: this shortens HID lifespan significantly.

If the HID bulbs are original, perhaps they need replacement after the hot re-striking and from age. Or maybe the ballasts are no longer up to par internally, perhaps a lighting specialist can load test them to verify. I doubt you have wiring problems, but who knows…I haven’t checked myself!

Who really knows how to arm-chair this query? What say you, Best and Brightest?

 

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry.

 

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46 Comments on “Piston Slap: Affalterbach’s A-faltering Headlight!...”


  • avatar
    LeMansteve

    My E46 has a somewhat related problem. The passenger-side high beam shutter inside the Xenon headlight housing will sometimes stick in the “on” position when I turn the high beams off. For those unaware, the Xenon bulb is basically always on full power and aimed in a high-beam position. There is a shutter that covers part of the beam to give low beams. It opens when you switch on the high beams.

    Like Martin’s SLK, only going over a bump will wake it up and the shutter will close. I suspect his mechanic put some dielectric lube on the bulb contacts and the lube degraded or washed out over time. My problem seems to happen more often if I use the high beams frequently. I have yet to properly diagnose it but I suspect there is a loose connection somewhere.

  • avatar
    FractureCritical

    if the mechanic applied dielectric grease to the connection and that helped, I’d likey pull all the plugs in the system, clean them, inspect the wires and contacts for corrosions or breaks, and put good fresh dielectric grease in everything. Remeber that shorts can track on carbon scoring or even dry rust stains, so get those too.

  • avatar

    Not to hijack the thread, but I have a related problem. In my Ford Ka, the instrument gauge lights go off in similar conditions (bumps, stops, gear changes), though the warning lights don’t. The first time it happened, smacking the plastic around the cluster would turn it back on, but that stopped working. Then I took it to an electrician who fixed the wiring and that worked for a couple of months. Then it started again and no amount of smacking helps (neither turning the lights on or off).

    So I took it to him again, he kept it a week and he said he was stumped as the wiring was ok as was the current. So I took it to another guy who said his only solution would be to change the whole instrument cluster. Of course, I don’t want to do that ’cause it’s expensive and I suspect it wouldn’t make the problem go away.

    So, all I can say is that lighting problems are a bitch!

    • 0 avatar
      golden2husky

      You’d love my brother’s old Saab 900 that had a wiring fault that caused the tach to plunge to zero when the left turn signal blinked on, then back to normal when the blinked off…a bad ground inside the dash that took 800 bucks to find and repair.

      Regarding the OP, moving components is an easy way to check but my concern is that the other side does the same thing, although with much less frequency. It could be that both sides are just aging out. Not familiar with the MB setup but if the unit is just powered by 12v (input into the assembly), perhaps you could identify the feed to the assembly ahead of time and when they go out again, see if you have 12 volts to the unit. No voltage present means that you do have a wiring problem. My instinct is the unit itself but before spending for nothing I would want to do all I could to rule out as much of the wiring as possible…

    • 0 avatar
      DenverMike

      Marcelo, Bypass the factory wires and power it yourself. That way you know it’ll work as it should.

      • 0 avatar

        Note taken, thanks DenverMike.

        • 0 avatar
          Sigivald

          Better advice than it might sound (because it can sound pretty sarcastic) – factory light wiring often runs the actual power for the lights through the light switch.

          Through small-gauge wires and a (comparative) lot of connections. All of that can lead to voltage drop from resistance, and dimmer lights (at least in the non-HID world; no idea what a voltage drop does to HIDs going into the ballast) – and more places for a fault to occur. This is especially relevant as the car ages, and contacts slowly corrode or get dirty.

          On my old truck and my current beater daily driver, I had/have fused lines from the battery straight to a relay block, and the relays are controlled by the unmodified stock wiring harness, but the lights themselves are powered straight [With a fuse, again! Don\'t skip that part unless you like engine compartment fires.] off the battery.

          Trying something like that would eliminate a fair number of possible faults.

          • 0 avatar
            danio3834

            “factory light wiring often runs the actual power for the lights through the light switch.”

            Not really on much made in the last decade.

          • 0 avatar
            claytori

            +1 on this if your car doesn’t have a separate headlight relay. While your at this mod, put in heavier wiring. I have #12 wire on mine.

    • 0 avatar

      Marcelo,

      Clean the copper contacts between the cluster and the lights/harnesses. Most clusters have a printed circuit, and the connections get oxidized and go bad. Clean them with a pink eraser (pink because they have more bite) like the one on a pencil.

      BTW, did you get my email?

      • 0 avatar

        I would think the electricians did that. I have always wondered if that could be it. BTW, could my problem be some sort of heating problem? I mean the light always works when you light it up and after about 5 to 15 min the going out and coming back on starts. Usually it just turns off, though sometimes it dims a little before going out. Then anything from seconds to a couple of minutes it turns back on, stays on from seconds to minutes, goes off again, then on again, then off again. I sometimes wish it just stay out forever as then a fix could be found (probably)…

        BTW, you got mail!

        • 0 avatar
          FuzzyPlushroom

          I’m not sure how the Ka’s instrument panel is laid out, but it could be a bad solder joint as well, particularly if it’s only one bulb that goes out. I know that’s what knocks out the gauges/lights in old Volvo 7/9-series clusters.

          • 0 avatar
            krhodes1

            +1

            Especially if it is a heat thing, almost inevitably it is a bad solder joint. I too have fixed several Volvo and Saab instrument panels that had gone wacky.

            For the OP, sure sounds like a dying ballast to me. For that car, are the ballasts separate or built into the bulbs? This is very common on late model Saabs with HID headlights, on those the ballast is built in and replacing the bulb solves the problem. One of the many reasons I have no use for HID lights, too complex and too expensive compared to the improvement over a GOOD set of halogens.

          • 0 avatar
            Power6

            The increase in lightis useful if you like driving though.

            I suppose it depends on the implementation, i just replaced the 12 year old original bulbs in my Lexus, not because they burnt out but they were fairly bluish. Bulbs werent cheap but the latest ones dont go blue as quick so car will be gone before it needs new bulbs. The HIDs absolutely rock the halogens in the old ES.

    • 0 avatar
      MRF 95 T-Bird

      I always wished us Americans were offered the Ka. It would have been a fine entry level vehicle for Ford to compete with the far worse Chevy Aveo. Could it have been as bad as the previously offered Mazda based mis-named Aspire?

      • 0 avatar

        Me thinks much too small for you guys. If your American Ford Festiva was the same as the Euro (and Brazilian) Fiesta of the time, the Ka is based on its platform, albeit slightly shortened IIRC. A Mazda Aspire, have never seen one. Is it a real Mazda product or based on some Ford (like the B200)?

      • 0 avatar

        just checked and according to wiki the Mazda Aspire and Ford Festiva are in fact Mazda cars and have nothing to do with the Euro Ford Fiesta. Don’t know about the Aspire/Festiva but the Fiesta was considered a very good driver’s car, specially in that late 80s to 90s configuration that really doesn’t exist anymore. These very small subcompacts have all grown very much and become more sophisticated, but losing some of the handling that made them great to drive (probably due to wait). The new cars of comparable size like the 500 or VW up! seem to be too tall and heavy to deliver the same thrills of those previous cars. Though surely more comfortable and safe, it seems to me that the new very small cars are at the beginning of their development while the old Fiesta/Clios/205 were at their pinnacle when the market moved on.

  • avatar
    DenverMike

    It’s most likely in the turn signal and hi/lo switch combo, as it’s the weakest link. Either way, bypass the mess with a ‘rewire’ as if you were installing aftermarket fog lights.

    Use heavy gauge wire, like 12ga and heavy duty relays. Mount the relays behind the headlights and run power direct from the battery. Use 18-22ga wire from a parking light source to trigger the relays.

    The headlights will be ON anytime the parking lights are ON.

    • 0 avatar
      golden2husky

      There is a company called SUVLights that sells kits to do just this…

    • 0 avatar
      Power6

      Bad diagnosis. It happens to one headlight at a time it is not a switch problem. Btw this car is new enough that likely body computer is controlling the lights rewiring would be labor intensive and not gain anything, HIDs are not as voltage sensetive a relay harness will not make them brighter. This benz is not old enough to be hacking up wires and bypassing body controllers but thats just MHO.

      This is most likely a ballast issue.

      • 0 avatar
        Sigivald

        Agreed in general.

        Though if it IS a wiring problem between the battery-to-switch-to-controller system, and the lights, bypassing that would reveal what section of the system the problem was in.

        And if you do the “conversion” correctly you don’t need to modify a single wire of the stock harness, just plug *into* it to get a control signal.

        But that’s a lot of work and some moderate (okay, not bad for anything with AMG in the name) to *maybe* eliminate a few possible causes…

        I agree that checking the ballast (and bulbs) first makes more sense than anything else…

        • 0 avatar
          Power6

          Its been decades since a car has been made that does not have a headlight relay.

          The harness idea is fine if you trigger from the stock headlight wiring of course if those outputs are flaky…

          Denver mikes theory and solution would involve custom wiring back to the switch and bypassing modules. Perfectly fine on an old basket case, but total waste of effort on a modern car that you would like to restore to original operation. The switch is not the problem anyways given the problem reported.

    • 0 avatar
      Battles

      Even on a Benz this old, a switch problem will generate an error code on the OBD.
      The bloke with the problem doesn’t say if his mechanics have checked car on an M-B STAR rig or just a regular code reader.
      I’m going with ballasts (and new bulbs due to the workaround).

  • avatar
    Land Ark

    I guess this is where we post headlight gremlin stories.
    My wife’s 06 Z4si has rage inducing trouble. The first issue is that the halo will randomly not work and work (each about 50% of the time). It isn’t related to hitting bumps or weather (she only drives it on sunny days). The next issue she encountered was that the low beams will randomly go out. The problem is when one goes out, and you turn the lights off and on, that one that was out will come on and the one that was on will go out. And it doesn’t change every time, so you can turn them off and on 5 times and get a random side out each time. Sometimes both.

    • 0 avatar
      Battles

      Is it the HID angel eyes type headlights?

      • 0 avatar
        Land Ark

        As far as I know, yes. But only the driver’s side angel eye gives her trouble.

        • 0 avatar
          Battles

          The lamp units won’t be interchangable but maybe the ballasts will?
          Swapping them might move the problem to the other lamp and move your investigations further on a bit.
          Are they original parts?

          Gawd, this is the fourth post I’ve made on this thread saying “it’s the ballasts!” but my experience with xenons was not entirely positive due to what seemed like very fragile OEM ballasts.

          • 0 avatar
            Land Ark

            I thought about the blasted ballasts. But I looked up the replacement cost and decided to take apart the front end and jiggle some wires.
            The halo problem was mostly cured by pulling on the wire inside the light that I deduced was for it. If I held it taught, it worked. Let it go and sometimes it didn’t.
            The fix I came up with for the alternating non-functioning low beam after putting the front end back together was to not turn on the headlights.
            I will not go out of my way to acquire HIDs for any future car purchases. What a headache.

          • 0 avatar
            Sigivald

            “The halo problem was mostly cured by pulling on the wire inside the light that I deduced was for it. If I held it taught, it worked. Let it go and sometimes it didn’t.”

            Bad connection or a broken wire (like, broken internally).

            Might not be worth the EFFORT to repair, but I’d bet a dollar, Terry Pratchett style, on one of those being the cause.

  • avatar
    Battles

    This sounds like the ballast. People on the Benz forums call it a lazy ballast because most people start getting the problem when one side or the other is noticably slower at starting up than the other, but lots of people report the need to switch off and on again due to one side or the other failing.

    They don’t seem to be lifed very long, my W203 needed a couple of sets of ballasts while it was still in warranty but the W210 was out of warranty and I had to replace them myself.

    Like Sajeev says, you’ve probably humped the bulbs too by the hot cycling to work around the problem.

    - Edited to say –
    Have you had the car on a STAR diagnostics rig?
    A switch/CANBUS/wider electrical problem will be generating errors but the Xenon lighting system is virtually isolated on cars of that era, it doesn’t report to the OBD so won’t show up there.
    That might help you rule a wider problem in or out and concentrate on the Xenon system.

  • avatar
    william442

    Our Thunderbird did the same. Never fixed.

  • avatar
    segfault

    When I had a BMW 540i, the driver’s side xenon would always take longer to come on than the passenger’s side. Shortly after I noticed this, the ballast caught fire (luckily, no damage other than the ballast)… One of the reasons I no longer own the car.

  • avatar
    CoreyDL

    So being that I dunno much ’bout them HID’s, and since it sounds like this is an issue with older HID lights, when did hot re-striking become a non-issue? Some redesign of the bulb in the 2000s?

    RE: That photo. It’s the most 90s looking shiny-type mirrored building, with a very 90s looking shiny car parked out front. Perfect.

  • avatar
    danio3834

    My first guess would be the ballast as well, however I would definitely check the circuitry first. You said you checked it, how? Using schematic, the power and ground circuits should be independently load tested using something like a 5A bulb. Then wiggle test the harness. If the bulb ever appears dim when testing, you can check the voltage drop accross the bulb. It should be within .25V of source voltage. If not, you have high resistance somewhere. Don’t forget to check connectors for corrosion, pushed out pins or spread pins that could make bad contact.

    A short to ground on the feed circuit *should* pop the fuse, but might not. You can check for continuity to ground using your meter, or use a powered test lamp with the circuit isolated to see if wiggling the harness will complete the circuit and light the lamp.

    Most people would probably just go ahead and replace the lamp and/or ballast, then check the circuitry when it still doesn’t work, but I prefer to check everything first.

    • 0 avatar
      danio3834

      I say *should* pop the fuse, if it even uses a fuse as circuit protection. It might have a field effect transistor in a body control module, however a circuit fault will typically cause those to shut off output on the circuit unit the fault is repaired and cleared.

  • avatar
    LeMansteve

    Whatever diagnosis you perform, DO NOT touch the Xenon bulbs with your bare hands. AFAIK body oils and dirt are bad for these bulbs.

  • avatar
    schmitt trigger

    Many, if not most of the electronic modules have a feature called undervoltage lockout. If the voltage dips for a certain time-volt period, the unit resets to “protect” the assembly or the vehicle.

    Unfortunately, old vehicles are full of those glitches. Traditionally, with an old fashioned incandescent lamp, those glitches would be all but invisible, and at worst the lamp would yellow a bit. Not any more with electronic assemblies.

    This is similar to analog vs high def TV.
    If you remember, with a poor reception analog signal, one would see a snowy horrible picture, but an image could still be seen. With HDTV, the picture is perfect until it reaches a certain signal level where it will blank out completely.

    Glitches have become such a gremlin in automotive electronic assemblies that most car manufacturers are now specifying full module functionality with glitches lasting up to 5 milliseconds.
    5 milliseconds may appear to be very short time period, and indeed it is, but to a microcontroller that is a loooooong time.

    Glitches are notoriously difficult to find, even with the correct test instrumentation.

  • avatar
    Audiofyl

    I didn’t see mentioned if you get a bulb out error in your instrument cluster when the lights begin to flicker.

    I would think its a ballast or connection to said ballast that is causing the issue.

    Mercedes kill the bulb output when it senses an error due to lack of load presented on the individual lighting circuit. The controller may attempt to get a functioning light by turning it off and on multiple times. Example: if you replaced a Mercedes marker bulb with an equivalent led bulb (sans load correcting circuitry) it will light briefly followed by flicking off and on and an error message about a light out in the instrument cluster.

    • 0 avatar
      kyngfish

      Hi, thanks for the feedback. This post is about my car. The lightbulb sensor does come on in my instrument cluster – that’s how i know to flick the lights. What I don’t understand, is why the lubricant fixed it for months? also this problem hasn’t occurred now for around 5 months. What gives?

      • 0 avatar
        claytori

        Maybe the Xenon’s strike better in warm weather. Based on my experience, slow start and intermittent drop-out signifies a bad bulb. Cheap and easy to fix. Check Amazon for the bulbs, a fraction of dealer cost. BTW, bulb life is about 1000-1200 hours. On a Euro car that has the low beams on all the time this only gets you about 2 years. Also check out the stuff at Daniel Stern’s website.

        • 0 avatar
          kyngfish

          @claytori – just as a followup, I switched sides on the bulbs to see if the problem would shift to the driver’s side when I moved the bulb. Sure enough, the driver’s side went out, which indicates a bulb issue. I did order some D2Rs from ebay, but it turns out for some reason that the dimensions on the Philips bulbs were SLIGHTLY off from the OSRAM OEM. The bulb got stuck in the ignitor and I had to beak the bulb housing to get it out. I spent 150 at NAPA to get a set of GE bulbs. So far everything is fine.


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